14.70 Transmission Systems

14.70.2 State the purpose of a helicopter transmission system.

Purpose of a Helicopter Transmission System

• To transmit power from the engine to the main and tail rotors
• To reduce engine RPM to suitable rotor RPM
• To drive essential accessories (e.g. generators, pumps)

Summary:
The transmission system transfers and adjusts engine power to drive the rotors at the correct speed.

14.70.4 Describe the function(s) and operation of the following transmission system components:

(a) main rotor gearbox;

Function:

• Reduces engine RPM to the correct rotor RPM
• Transmits power from the engine to the main rotor
• Drives accessories (e.g. pumps, generators)

Operation:

• Receives high-speed input from the engine
• Uses gear reduction stages to lower RPM
• Delivers torque to the main rotor mast
• Provides mounting for the rotor head assembly

Summary:
The main rotor gearbox reduces engine speed and delivers power to the main rotor at the correct RPM.